When leaders of the 109-year-old Isabella Stewart Gardner Museum unveiled its $114 million addition today, they did it with an eye toward the past, referencing the project not as an expansion but as a “preservation.”

Isabella Stewart Gardner herself could never have anticipated that her palace-museum would grow to the point that roughly 200,000 visitors stream in each year, officials said. The influx created stress on the palace and made it hard for the Gardner Museum to expand its programs. The new, glass-and-copper-clad building, connected to the original museum through a 50-foot-long glass passageway, should solve those problems.

The 70,000 square-foot construction includes a music hall, greenhouse, gallery, gift shop, restaurant and expanded room for educational programs. The building will serve as the Gardner’s new entrance, with visitors entering the palace through a new, 50-foot long glass walkway.

Today’s events, open to the media, marked the start of 10 intense days that will include special unveilings for donors and trustees and performances by, among others, cellist Yo-Yo Ma.